Field of the Disclosure
The present disclosure relates to a sheet feeding device and an image forming device, and in particular relates to the same provided with a sheet stacking member that is capable of being lifted and lowered and that stacks sheets on a sheet containing unit.
Description of the Related Art
Conventional image forming devices, such as printers, copiers, and facsimiles, include a sheet feeding device that feeds sheets that is contained in a sheet containing unit provided detachably to a main body of the device to an image forming unit by sending out the sheets with a sheet feeding unit. In the sheet feeding device, a lift plate that is a sheet stacking member on which the sheets are stacked is provided, so as to be capable of being lifted and lowered, in a sheet feeding cassette that is the sheet containing unit. When feeding the sheets, the lift plate is lifted such that the sheets are urged against a sheet feeding roller that is a sheet feeding unit. Furthermore, by having the sheet be in pressure contact with the feed roller, pressure contact force (hereinafter, referred to a sheet feeding pressure) is generated, and in a state in which the sheet feeding pressure is generated, the sheet feeding roller is rotated to send the sheets out.
Such a sheet feeding device is provided in the sheet feeding cassette with a lifter mechanism that is a lifting and lowering mechanism for lifting the lift plate, a gear and a motor that drives the gear is included in the main body of the device, and a drive unit that drives the lifter mechanism is provided. Furthermore, when the sheet feeding cassette is mounted, the lifter mechanism is connected to the drive unit, and subsequently, when the drive unit is driven, the lift plate is lifted with the lifter mechanism to a predetermined height that enables the sheet on the top to be sent out.
Incidentally, when replenishing the sheets, when changing the type of sheet, or when a sheet jam occurs, the sheet feeding cassette is drawn out from the main body of the device. When the sheet feeding cassette is drawn out as above, the connection between the lifter mechanism and the drive unit is released. In such a case, when the lift plate is in a lifted state, the lift plate is lowered by its own weight and the weight of the stacked sheets, and impacts the bottom surface of the sheet feeding cassette generating a noise with the impact. Note that the loudness of the sound of impact is prominent when there are no sheets stacked, in other words, when the sheet feeding cassette is drawn out when the lift plate is at its highest position.
Accordingly, in Japanese Patent Laid-Open No. 8-127434, in order to mitigate the sound of impact when the lift plate is lowered, for example, a damper is disposed inside a lifting and lowering mechanism and the lift plate is lowered slowly.
Note that in recent years, a need for sheet feeding devices to become more compact and to have a larger capacity is increasing. However, when a damper is disposed in the lifting and lowering mechanism, it makes it difficult to make the sheet feeding device more compact and the structure becomes complex, and further, since there will be a load caused by the damper when lifting the lift plate, load to the motor of the drive unit becomes larger.